A rotating cutting tool is a cutting tool known for cutting a workpiece material such as a metal. The cutting tool includes a body having a plurality of edge slots (insert pockets) on the periphery of its top end, and indexable inserts (cutting inserts) attached in the edge slots. The cutting tool further includes clamps for fastening the indexable inserts to the body in a removable manner, and screws each for adjusting the runout of the insert. The top surface of each adjustment screw is in contact with the seat surface of the corresponding insert. The adjustment screw is adjusted to position the insert.